A biofilm is a well-organized community of microorganisms that adheres to surfaces and is embedded in slimy extracellular polymeric substances (EPSs). EPS is a complex mixture of high-molecular-mass polymers (>10,000 Da) generated by the bacterial cells, cell lysis and hydrolysis products, and organic matter adsorbed from the substrate. EPSs are involved in the establishment of stable arrangements of microorganisms in biofilms (Wolfaardt et al. (1998) Microb. Ecol. 35:213-223; herein incorporated by reference in its entirety), and extracellular DNA (eDNA) is one of the major components of EPSs (Flemming et al. (2001) Water Sci. Technol. 43:9-16; Spoering et al. (2006) Curr. Opin. Microbiol. 9:133-137; each herein incorporated by reference in its entirety). Bacteria living in a biofilm usually have significantly different properties from free-floating (planktonic) bacteria of the same species, as the dense and protected environment of the film allows them to cooperate and interact in various ways. One benefit of this environment is increased resistance to detergents and antibiotics, as the dense extracellular matrix and the outer layer of cells protect the interior of the community. In some cases antibiotic resistance can be increased a thousand-fold (Stewart et al. (2001) Lancet 358:135-138; herein incorporated by reference in its entirety). Biofilms can be formed in various bacterial species (e.g., Acinetobacter sp. (e.g., A. baylyi, A. baumannii), Staphylococcus aureus, Stenotrophomonas maltophilia, Escherichia coli (e.g., E. coli K-12). The formation of biofilms by such species is a major determinant of medical outcome during the course of colonization or infection. For example, Acinetobacter spp. frequently colonize patients in clinical settings through formation of biofilms on ventilator tubing, on skin and wound sites, medical tubing, and the like, and are a common cause of nosocomial pneumonia.
As biofilms are complex structures formed of various elements, their removal or disruption traditionally requires the use of dispersants, surfactants, detergents, enzyme formulations, antibiotics, biocides, boil-out procedures, corrosive chemicals, mechanical cleaning, use of antimicrobial agents, inhibiting microbial attachment, inhibiting biofilm growth by removing essential nutrients and promoting biomass detachment and degradation of biofilm matrix (Chen XS, P. S.: Biofilm removal caused by chemical treatments. Water Res 2000; 34:4229-4233; herein incorporated by reference in its entirety). However, such classical removal or disruption methods are not efficacious or feasible in all situations where biofilm formation is undesirable.
Additional methods for undesirable bacteria in biofilms are needed.